Multilateral completion systems allow the drilling and completion of multiple wells within a single wellbore. In addition to the main wellbore, there are one or more lateral wells extending from the main wellbore. This allows for alternative well-construction strategies for vertical, inclined, horizontal, and extended-reach wells. Multilaterals can be constructed in both new and existing oil and gas wells. A typical installation includes two laterals; the number of laterals would be determined by: the number of targets, depths/pressures, risk analysis, and well-construction parameters.
Multilateral systems combine the advantages of horizontal-drilling techniques with the ability to achieve multiple target zones. The advantages of horizontal drilling include: higher production indices, the possibility of draining relatively thin formation layers, decreased water and gas coning, increased exposure to natural fracture systems in the formation, and better sweep efficiencies.
Depending on the type of multilateral design used, the target zones can be isolated and produced independently—or produced simultaneously, if commingled production is allowed or if a parallel string completion is used.
However, while there are multiple multilateral designs available, many are complex and expensive to implement, and there remains a critical need to ensure the use of such multilateral junctions in a wide array of wells, while maintaining hydraulic and mechanical integrity.